This is an extension of the basic pattern matching scheme intended to improve support for mapping complex xml-schema.
It is intended to be a minimal extension of the standard rules big enough to support complex schema but without the
full generality offered by more exotic matching pattern rules.

When should you use this rather than the original?

This pattern-matching engine is complex and slower than the basic default RulesBase class, but offers more
functionality:

Universal patterns allow patterns to be specified which will match regardless of whether there are
"better matching" patterns available.

Parent-match patterns (eg "a/b/?") allow matching for all direct children of a specified element.

Universal Match Patterns

The default RulesBase pattern-matching engine always attempts to find the "best matching pattern", and will ignore
rules associated with other patterns that match but are not "as good". As an example, if the pattern "a/b/c" is
associated with rules 1 and 2, and "*/c" is associated with rules 3 and 4 then element "a/b/c" will cause only
rules 1 and 2 to execute. Rules 3 and 4 do have matching patterns, but because the patterns are shorter and include
wildcard characters they are regarded as being "not as good" as a direct match. In general, exact patterns are better
than wildcard patterns, and among multiple patterns with wildcards, the longest is preferred. See the RulesBase class
for more information.

This feature of preferring "better" patterns can be a powerful tool. However it also means that patterns can interact
in unexpected ways.

When using the ExtendedBaseRules, any pattern prefixed with '!' bypasses the "best match" feature. Even if there is
an exact match or a longer wildcard match, patterns prefixed by '!' will still be tested to see if they match, and if
so their associated Rule objects will be included in the set of rules to be executed in the normal manner.

Parent Match Patterns

"*/a/b/c/?" matches any child whose parent matches "*/a/b/c". The longest
matching still applies to parent matches but the length excludes the '?', which effectively means that standard
wildcard matches with the same level of depth are chosen in preference.

Ancestor Match Patterns

These will match elements whose parentage includes a particular sequence of elements.

"a/b/*" matches any element whose path starts with 'a' then 'b'. Exact parent and parent match rules
take precedence. The longest ancestor match will take precedence.

"*/a/b/*" matches any elements whose path contains an element 'a' followed by an element 'b'.
The longest matching still applies but the length excludes the '*' at the end.

Completely Wild Patterns

Pattern "*" matches every pattern that isn't matched by any other basic rule.

Pattern "!*" matches every pattern.

Using The Extended Rules

By default, a Digester instance uses a RulesBase instance as its pattern matching engine. To use an
ExtendedBaseRules instance, call the Digester.setRules method before adding any Rule objects to the digester
instance:

The most important thing to remember when using the extended rules is that universal and non-universal patterns are
completely independent. Universal patterns are never affected by the addition of new patterns or the removal of
existing ones. Non-universal patterns are never affected by the addition of new universal patterns or the
removal of existing universal patterns. As in the basic matching rules, non-universal (basic) patterns
can be affected by the addition of new non-universal patterns or the removal of existing
non-universal patterns, because only rules associated with the "best matching" pattern for each xml element
are executed.

This means that you can use universal patterns to build up the simple parts of your structure - for example defining
universal creation and property setting rules. More sophisticated and complex mapping will require non-universal
patterns and this might mean that some of the universal rules will need to be replaced by a series of special cases
using non-universal rules. But by using universal rules as your backbone, these additions should not break your
existing rules.

match

Return a List of all registered Rule instances that match the specified nesting pattern, or a zero-length List if
there are no matches. If more than one Rule instance matches, they must be returned in the order
originally registered through the add() method.